Technical Field
The present invention relates to a cell clustering method and a spectrum overlapping multiplexing method based on the cell clustering method, also relates to a communications device for performing the method, and belongs to the field of wireless communications technologies.
Related Art
Currently, see the following examples for common cell clustering methods.
Method 1: A Clustering Method Based on a Graph Theory
The method mainly includes using edges between nodes to represent interference, abstracting inference values as interference weights, and then performing clustering by drawing interference diagrams by using different methods. Some methods include decomposing sub-diagrams by using K-means, where each sub-diagram is used as a cluster. Some include setting a cell distance, a channel gain, and the like as similarities based on the similarities, so that cells having large similarities are classified into a cluster, and then inter-cluster interference management and intra-cluster resource scheduling are performed.
Method 2: A Clustering Method Based on a Smallest Interference
The quantity N of clusters is first determined. At first, each small cell is used as a cluster, and then interference between clusters is calculated according to the following formula. Afterwards, two clusters having a smallest interference between the two clusters are found and are merged into a large cluster. Then, iteration of the loop is performed until the quantity of clusters reaches the preset quantity N of clusters and all small cells are added into different clusters.
      I    ⁡          (                        C          k                ,                  C          v                    )        =            1              |                  C          k                |                  +                      |                          C              v                        |                                ⁢                  ∑                              i            ,                          j              ∈                              C                k                                      ,                          C              v                                                          i              ≠              j                        ⁢                                                                    ⁢              P                  i          ,          j                    
I(Ck,Cv) is an interference value between a cluster k and a cluster v. |Ck|,|Cv| are respectively the quantities of cells in the cluster k and the cluster v. Pi,j is interference receive power (an RSRP value) of Cellj to Celli in the cluster k and the cluster v.
Method 3: A Clustering Method Based on Interference Reduction (a CCIR Method for Short)
The quantity N of clusters is first determined, and then a cell that is interfered to a largest extent is placed into a first cluster, to initialize the first cluster. Then, (N−1) cells having a largest interference with existing clusters are found in sequence to complete an initialization process of N clusters. Subsequently, a cell having a largest interference with all the existing clusters is found and added into an existing cluster having a smallest interference with the cell. Iteration of the loop is performed until all cells are added into the N clusters.
A calculation formula of interference of cells to clusters is as follows:
                              I          ⁡                      (                                          Cell                i                            ,                              C                k                                      )                          =                              ∑                                                            j                  ∈                                      C                    k                                                  ⁢                                                                                                                RSRP                                      i                    ,                    j                                                  ≥                                                      TH                    —                                    ⁢                  RSRP                                                              ⁢                      P                          j              ,              i                                                          (        1        )            
I(Celli,Ck) is an interference value of a cell i to a cluster k, Pj,i is interference receive power (an RSRP value) of Celli to an element Cellj in the cluster k, and Cellj is an interference neighboring cell of Celli.
In the foregoing cell clustering methods, under an ultra dense networking condition, when the quantity of interference cells increases, and there is a relatively large quantity of cells in clusters in a later period of mergence of clusters, defects start to appear. For example, granularities of mergence of clusters are excessively large, and because only an average interference between clusters is considered, a strong interference between small cells in clusters cannot be eliminated and alleviated. In the CCIR method, only interference between cells is considered, and improvement of a network capacity and a network coverage level cannot be ensured.